001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.metrics2.lib;
020    
021    import org.apache.hadoop.classification.InterfaceAudience;
022    import org.apache.hadoop.classification.InterfaceStability;
023    import org.apache.hadoop.metrics2.MetricsInfo;
024    import org.apache.hadoop.metrics2.MetricsRecordBuilder;
025    
026    /**
027     * A mutable int counter for implementing metrics sources
028     */
029    @InterfaceAudience.Public
030    @InterfaceStability.Evolving
031    public class MutableCounterInt extends MutableCounter {
032      private volatile int value;
033    
034      MutableCounterInt(MetricsInfo info, int initValue) {
035        super(info);
036        this.value = initValue;
037      }
038    
039      @Override
040      public synchronized void incr() {
041        ++value;
042        setChanged();
043      }
044    
045      /**
046       * Increment the value by a delta
047       * @param delta of the increment
048       */
049      public synchronized void incr(int delta) {
050        value += delta;
051        setChanged();
052      }
053    
054      public int value() {
055        return value;
056      }
057    
058      @Override
059      public void snapshot(MetricsRecordBuilder builder, boolean all) {
060        if (all || changed()) {
061          builder.addCounter(info(), value);
062          clearChanged();
063        }
064      }
065    
066    }